Interestingly enough, 12% of Computer and Information Science degrees in the US are awarded to Blacks [1][2]. That is in contrast to 9% that are awarded to Asians. But also, 13% of the population is Black, and 5% of the population is Asian [3]. So, it would be expected that more Asians than Blacks are employed at Tech companies. However, the high ratio of Asians (vs. Whites, Blacks, and Latinos) employed at Bay Area tech companies shows some discrepancies. But, it may only be that Asians are more willing to relocate.
Sorry, but unfortunately your conclusions are wrong. More Asian people in absolute numbers and in percentage get "computer and information science" degrees. In fact, the trend has been negative for blacks.[1]
[1]: https://nces.ed.gov/programs/digest/d11/tables/dt11_301.asp
[2]: I could only find 2010 data, but I expect it's generally consistent.
[3]: https://www.census.gov/quickfacts/table/PST045216/00